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On Small Mammal Sympatry in the Southeastern Amazon and Ecological Relationships with Brazil Nut Dispersal and HarvestingSolorzano-Filho, Jorge Alberto 03 March 2010 (has links)
The Amazon rainforest harbors the planet's highest biodiversity among terrestrial ecosystems; however, the biology and ecology of most of its species are unknown. Niche partitioning is considered a key factor allowing species co-existence, especially for morphological similar species such as spiny rats of the genus Proechimys. I examined the extent to which habitat differentiation, species body mass, and diet could explain the community composition of small mammals at a site in the southeastern Amazon. Moreover, I radio-tagged sympatric species of Proechimys spp. and Mesomys stimulax (an arboreal spiny rat) to obtain detailed autoecology information, including habitat use and use of space. I found support for niche partitioning among species and associated small mammal species with distinct successional phases of gap dynamics. I also observed among Proechimys spp. a typical polygynous organization: females appeared to be territorial against females of any species of their genus; but male territories overlapped with those of several females. Mesomys stimulax showed evidence of monogamy and possible sociality, although sample sizes were small. To identify the importance of small mammals as seed disperser of Brazil nut seeds, I conduct experiments using a combination of fluorescent powder, seed exclosures, and track plates in forests with and without Brazil nut groves, and in forests with and without Brazil nut harvesting. Among small mammals, only Proechimys spp. removed, dispersed, and preyed upon Brazil nut seeds. Proechimys spp. sometimes scatterhoarded these seeds, and hence have the potential to play a significant role in recruiting new Brazil nut trees. I also trapped small mammals and measured forest structures on the same sites used for the seed dispersal experiment, to determine the ecological effects of Brazil nut harvest on small mammal communities; however, my results showed little evidence of changes associated with the seed exploitation. My results highlight the importance of habitat heterogeneity in structuring small mammal communities, and indicate that forest management practices that alter habitats, such as partial logging, also can be expected to alter small mammal composition and diversity. Proechimys spp. have the potential to play an important role in the ecological restoration of intensive exploited Brazil nut groves.
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Les possibilités de dispersion et éléments d'habitat-refuge dans un paysage d'agriculture intensive fragmenté par un réseau routier dense : le cas de la petite faune dans la plaine du Bas-Rhin / Dispersal possibilities and refugial habitats in a intensive agricultural landscape fragmented by a dense road network : the case of small animals in the Bas-Rhin plainJumeau, Jonathan 16 October 2017 (has links)
La fragmentation des paysages et des habitats induite par les infrastructures linéaires de transport terrestres est une des principales causes de la perte de biodiversité actuelle. Parmi ces infrastructures, la route est un acteur majeur de fragmentation, d’autant plus qu’elle possède des effets propres dus au trafic circulant qui induit des collisions véhicule-faune et une pollution des paysages. Afin de diminuer ces effets négatifs, des mesures de réduction sont mises en place, notamment des passages à faune permettant de faire traverser la faune de part et d’autre des voies. La route crée aussi de nouveaux habitats potentiels pour les espèces de la petite faune dans des paysages anthropisés et fragmentés. Dans ce mémoire sont démontrées (1) la potentialité d’habitat de différents éléments routiers ; (2) la possibilité de prédire les collisions véhicule-faune afin de positionner au mieux les mesures de réduction ; (3) l’importance de la méthodologie dans l’évaluation de l’efficacité des passages à faune ; et (4) la possibilité d’améliorer les passages à faune existants. Ces résultats permettront d’améliorer les stratégies de défragmentation des paysages. / Habitats and landscape fragmentation, caused by linear land transports infrastructures, is one of the major cause for the current loss of biodiversity. Among those infrastructures, road is a major cause of fragmentation, especially as it possess specific traffic-linked effects, which induces wildlife-vehicles collisions and landscape pollution. In order to decrease those negative effects, mitigation measures are taken, among which wildlife crossings, enabling wildlife to cross the road. Road also creates new potential habitats for small wildlife species in anthropogenic and fragmented landscapes. In this essay are shown (1) the potential as habitat of different road-linked elements; (2) the possibility to anticipate wildlife-vehicles collisions in order to improve the position of mitigation measures; (3) the importance of methodology in the evaluation of wildlife crossings effectiveness; and (4) the possibility to improve existing wildlife crossings. Those results will allow improving landscape defragmentation strategies.
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Relations hôtes – parasites zoonotiques : diversité, aspects évolutifs et implications épidémiologiques. Le cas de la leptospirose dans les îles du sud-ouest de l’océan Indien / No English title availableGomard, Yann 08 December 2015 (has links)
La leptospirose est considérée comme la zoonose la plus répandue au monde mais les incidences sont les plus élevées dans les régions tropicales et en particulier sur les îles. Les îles du Sud-Ouest de l'Océan Indien ne dérogent pas à la règle puisque la maladie y représente un problème de santé humaine majeur sur plusieurs îles, notamment aux Seychelles qui enregistrent un des plus fort taux d'incidence humaine au monde. Sur la base des données disponibles, l'épidémiologie humaine apparait contrastée à l'échelle de la région : les cas cliniques sur Mayotte résultent d'infections par quatre espèces de leptospires distinctes alors qu'à La Réunion ou aux Seychelles, une seule espèce est à l'origine de la grande majorité des cas cliniques. L'objectif général de cette thèse est d'identifier certains des déterminants de cette épidémiologie singulière. Nous avons dans un premier temps complété les informations humaines en investiguant la leptospirose en Union des Comores, pays n'ayant jamais rapporté de transmission autochtone. Nos résultats indiquent que les populations humaines y sont exposées à des antigènes de leptospires comparables à ceux retrouvés sur l'île voisine de Mayotte. Ce résultat suggére que l'absence de leptospirose sur certaines îles est le résultat d'un déficit de surveillance. Nous avons ensuite caractérisé la diversité génétique des leptospires au sein de la faune de certaines îles, caractérisées par des niveaux d'endémisme élevés à même d'être en partie à l'origine de cette épidémiologie contrastée. Nous décrivons d'une part une importante diversité des leptospires pathogènes chez les chauves-souris (Chiroptères) malgaches. Nous montrons d'autre part que cette diversité de leptospires n'est pas structurée géographiquement mais présente au contraire une importante spécificité d'hôte, résultant de différents processus évolutifs incluant co-spéciation et host-switch. Nous avons exploité cette spécificité d'hôte pour éclairer l'épidémiologie de la leptospirose à Mayotte, où nous montrons que l'importante diversité bactérienne impliquée dans les cas cliniques résulte de la présence de nombreux réservoirs, dont certains originaires de Madagascar. Ainsi, il apparaît que l'épidémiologie humaine de la leptospirose dans le SOOI est le reflet d'assemblages distincts de leptospires cosmopolites et autochtones/endémiques maintenus et excrétés par des réservoirs animaux particuliers. / Leptospirosis is considered as the most widespread zoonosis worldwide but the incidence levels are higher in tropical regions and particularly on islands. The South-Western Indian Ocean islands are no exception and the disease is of major medical concern in several islands notably in Seychelles, displaying some of the highest human incidence ever reported. Based on available data, the human epidemiology appears contrasted in the region: on Mayotte, human cases result from the infection with four distinct Leptospira species whereas on Reunion Island or Seychelles, a single species causes the majority of clinical cases. The main objective of this thesis is to identify some of the drivers of this singular epidemiology. We first completed the information available on this human disease in the region by investigating the leptospirosis situation in the Union of the Comoros, a country where no autochthonous transmission has been reported so far. Our results indicate that Comorian populations are exposed to Leptospira, which are antigenically comparable to those detected in the neighbouring island of Mayotte. This finding suggests that the apparent absence of leptospirosis in some islands rather reflects a lack of surveillance. We then investigated the genetic diversity of Leptospira on distinct islands home to distinct endemic animal species that may shed distinct Leptospira lineages and thus at least in part explain the contrasted epidemiology of leptospirosis in the region. Specifically, we describe a high diversity of pathogenic Leptospira within Malagasy bats (Chiroptera) and further show that Leptospira diversity is not structured by geography. Instead, we show that these Leptospira display a strong specificity towards their hosts, which may result from different evolutionary processes including co-speciation and host switching. Using this tight host specificity, we investigated the leptospirosis epidemiology on Mayotte, where we show that the important bacterial diversity reported in clinical cases is due of the presence of several distinct animal species acting as reservoirs, some of which introduced from the neighbouring Madagascar. Altogether, results presented herein combined to data produced by our lab suggest that the epidemiology of leptospirosis in the SWOI results from distinct assemblages of cosmopolitan and autochthonous/endemic Leptospira. Keywords : Leptospirosis, Leptospira, Chiroptera, small mammals, hosts-parasites associations, MAT, MLST, co-phylogeny, Madagascar, Mayotte, Union of Comoros, South-Western Indian Ocean.
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Small mammal and bird abundance in relation to post-fire habitat succession in mountain big sagebrush (Artemisia tridentata ssp. vaseyana) communitiesHolmes, Aaron L. 28 December 2010 (has links)
Fire is an important disturbance mechanism in big sagebrush (Artemisia
tridentata) communities, yet little is known about wildlife population dynamics during
post-fire habitat succession. I estimated the abundance of small mammals and birds in
relation to fire history in mountain big sagebrush (A.t. spp. vaseyana) communities on the
Sheldon National Wildlife Refuge in the northwestern Great Basin, USA. I employed a
chronosequence approach that took advantage of multiple wildfires that had occurred in
similar plant communities between 7 to 20 years prior to sampling.
Belding’s ground squirrel (Spermophilus beldingii) were approximately 10 times
as abundant in burned areas relative to adjacent unburned habitat regardless of the
number of years since a burn occurred. Deer mouse (Peromyscus maniculatus) was more
abundant on more recently burned sites, but not at sites closer to full vegetation recovery.
Great basin pocket mouse (Perognathus parvus), sagebrush vole (Lemmiscus curtatus),
and least chipmunk (Tamius minimus) abundance did not vary as a function of fire
history, but some variance was explained by habitat features such as rocky areas and the
canopy characteristics of sagebrush.
Bird diversity was higher in unburned habitats irrespective of the number of years
of recovery out to 20 years. Nine of the 12 most widely occurring species of birds in the
study have population densities influenced by fire or post-fire habitat succession to at
least 13 to 20 years following a burn. Sage Sparrow (Amphispiza belli), Black-throated
Sparrow (Amphispiza bilineata), and Spotted Towhee (Pipilo maculatus) occurred at
relatively low densities and were nearly restricted to unburned habitats. Green-tailed
Towhee (Pipilo Chlorurus), Gray Flycatcher (Empidonax wrightii), American Robin
(Turdus migratorius), and Brown-headed Cowbird (Molothus ater) occurred at lower
densities in burned areas than adjacent unburned areas although the relationship was not
strong for the latter two species. The magnitude of the difference in density between
burned and unburned sites within a landscape diminished with the number of years of
vegetation recovery for Green-tailed Towhee. Brewer’s Sparrow (Spizella brewerii)
occurred at lower densities relative to adjacent habitat in the most recent burn, but
occurred at higher densities after 20 years of habitat succession, suggesting a positive
response with a multiple decade lag period. Horned Lark (Eremophila alpestris) and
Vesper Sparrow (Pooecetes gramineus) respond positively to fire, but densities were
similar to unburned areas after 20 years of habitat succession.
An ordination analysis captured 86% of the variation in 12 bird species with 3
orthogonal axes. My research demonstrates that strong community structure exists for
birds associated with mountain big sagebrush habitats, and that fire influences
community structure for multiple decades. / Graduation date: 2011 / Access restricted to the OSU Community at author's request from Dec. 22, 2010 - Dec. 22, 2011.
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Vijabilnost populacije tekunice (Spermophilus citellus) pod uticajem promene klime i staništa / Viability of European ground squirrel population (Spermophilus citellus) under climate and land use change.Nikolić Tijana 24 October 2019 (has links)
<p>U radu je analiziran odgovor lokalnih populacija tekunice u Vojvodini na<br />promene uslova klime i korišćenja zemljišta. Odgovori populacija tekunice<br />(tipičnog predstavnika otvorenih staništa i idealnog model organizma) na<br />pomenute promene omogućiće razmatranje kako mere na regionalnom nivou: i)<br />mogu unaprediti zaštitu i očuvanje tekunice ii) ublažiti efekti promene klime i<br />korišćenja zemljišta iii) mogu usaglasiti razvoj poljoprivrede sa očuvanjem<br />biodiverziteta travnatih ekosistema. Kako bi se odgovorilo na pitanja i postavljene hipoteze u radu sprovedeno je terensko istraživanje, korišćen standardni prostorni pristup i ekološko modelovanje. Sve primenjene tehnike su komplementarne jedna drugoj u dobijanju odgovora na postavljena pitanja gde rezultati jedne analize predstavljaju ulazne podatke za drugu analizu. U tezi su korišćeni podaci dobijeni na osnovu terenskog mapiranja lokalnih populacija i podaci iz eksperimenta modelovanja kao i serija podataka dobijena cenzusom kolonija tekunica i terenskim uzorkovanjem zemljišta i vegetacije. Rasprostranjenje populacija oblikuju klimatski uslovi ali pored abiotičkih faktora uslovljavaju ih i biotički faktori i kretanje jedinki. Promena klime direktno utiče na distribuciju optimalnih uslova. Istraženo je u kojoj meri će doći do promene u distribuciji optimalnih uslova sredine za tekunicu. Potencijalna promena analizirana je uzimajući u obzir klimatski scenario Max Plank Instituta sa tri rcp projekcije i tri generisana prostorna scenarijadistribucije otvorenih travnatih staništa u Vojvodini. Sagledavanje mogućih efekata promene sredinskih uslova dalo je mogućnost da se ukaže na zone koja će biti ključne za očuvanje populacija tekunica i travnatih ekosistema u Vojvodini. Sledeće, s obzirom da disperzija jedinki, dostupnost resursa kao i delovanje lokalnih faktora ugrožavanja (barijere, menadžment staništa, varijabilnost sredinskih uslova, predatorstvo, poljoprivredne aktivnosti) oblikuju distribuciju populacija u prostoru, u radu je analiziran i uticaj promene ovih faktora na distribuciju populacija. Na području lokalnog slatino-stepskog koridora srednjeg Banata istražene su kompozicija biljnih vrsta, upravljanje na staništu, promena u kompoziciji okolnih poljoprivrednih kultura i dinamika populacije. Dobijene su informacije o efektima lokalnih uslova na prisustvo kolonija, veličinu kolonija i kondiciono stanje jedinki. Informacije dobijene u ovim poglavljima su kasnije korišćeni za formiranju seta kriterijuma radi karakterizacije svih mapiranih staništa u Vojvodini. Dalje, veliku ulogu u poljoprivrednom predelu imaju tranziciona staništa koja povezuju lokalne populacije. Identifikovanje koja tranziciona staništa koriste jedinke tekunice je ključno za očuvanje populacija i ublažavanje trena opadanja brojnosti. Na terenu su mapirani distribucioni obrasci lokalnih kolonija tekunice i istraženo je da li postoje razlike na lokalnom i predeonom nivou u distribuciji nastanjenih i napuštenih staništa na području Vojvodine. U radu je dalje analizirana mapirana mreža staništa lokalnih populacija i pretpostavljano je da populacije funkcionišu i održavaju se u okviru metapopulacione strukture. Sa druge strane, veličina i površina koju zauzimaju potencijalne metapopulacione struktura mapirane mreže staništa koje se razlikuju u odnosu na okupiranost, kapacitet i povezanost nisu bile poznate. Kako bi se kvantifikovale potencijalne metapopulacione jedinice i utvrdila vijabilnost svake definisane pojedinačne metapopulacione mreže korišćen je metod ključnog fragmenta. Mapirane mreže evaluirane su iz perspektive samog taksona i testiran je potencijalni disperzioni kapacitet. Proverena je permeabilnost predeonog matriksa između mapiranih staništa i identifikovani su potencijalni koridori za jedinke. Ovakav pristup daje uvid u koji deo predela je značajno i neophodno ulagati ograničena sredstva za zaštitu prirode unutar regiona Vojvodine. U tezi je na kraju ocenjen doprinos trenutne regionalne konzervacione prakse zaštiti staništa tekunice, dat pregled slabih tačaka i predlog predeono adaptacionih mera koji će doprineti zaštiti i očuvanju populacije tekunice kao i mozaika otvorenih travnatih staništa.</p> / <p>The study analyzes the European ground squirrel (EGS) population response to land use and climate change in Vojvodina. The response of the EGS population (typical species of open grassland habitats and the ideal model organism) to changes in environmental conditions in this region will enable consideration of following measures at the local and landscape level: i) effective protection and<br />conservation of the EGS and habitat it relay on; ii) climate change and land use mitigation and adaptation iii) how can we harmonize the development of agriculture and preserve the biodiversity of grassland ecosystem in agricultural settings. In order to answer the questions of this study, the field research was conducted, standard spatial approach and ecological modeling were employed. All applied techniques are complementary to one another in obtaining responses to the questions asked. The results of one analysis represent the input data for the following one. The data for the study were obtained: from EGS local populations’ field mapping, from the modeling experiment, the census campaigned and the field sampling of soil and vegetation. Distribution of populations, which in addition to abiotic factors are conditioned by biotic factors and movement of individuals were evaluated in the context of climate change. Climate change directly affects the distribution of optimalconditions. The potential changes in distribution of optimal environmental conditions for EGS were assessed by considering changes in abiotic factors and the availability of grasslands. The climate scenario obtained using a dynamic vegetation map with three rcp projections and three spatial scenarios for the distribution of open grasslands were used. The extrapolation of a suitable area obtained by presence only model Maxent gives the possibility to point to the zones that will be crucial for preserving the populations and grassland ecosystems in future. Dispersion of individuals, availability of resources and the operation of local threats (e. g. barriers, habitat management, variability of the central conditions, predation, agricultural activities) shape the distribution of populations in space and time. In the area of the local saline steppe corridor of the central Banat in Vojvodina i) the composition of plant species, ii) open grassland habitat management iii) changes in the composition of surrounding crops and iv) population dynamics of EGS have been investigated. The effects of local conditions on the presence, size of colonies and condition of the individuals of EGS were assessed. The information obtained in these chapters was later used to form a set of criteria for the characterization of all mapped habitats in Vojvodina. In the agricultural area, transitional habitats connect local populations of many species. Identifying transitional habitats which potentially can be used by focal species is key to protect and mitigate population decline. For this purpose distribution patterns of the colonies were mapped in the field. The haracteristics and differences among mapped patches at the local and sub landscape scale were detected and evaluated. Later in the study the network of mapped habitats patches was evaluated. It was assumed that mapped populations in Vojvodina function within several metapopulations networks. However, the size and area of potential meta-population networks are likely to differ in relation to occupancy, capacity and habitat connectivity. The knowledge of potential population units was scarce. In order to quantify the potential population units, to determine the viability and conservation priority of each defined habitat network the key patch approach was used. Mapped networks were evaluated from the perspective of the taxon itself and potential dispersed capacity was tested. The ermeability of the matrix area, connectivity of the mapped habitats and the distribution of potential corridors was verified. This approach gives an opportunity to assess to which part of the area and population it is necessary to invest limited resources for nature protection in Vojvodina.The contribution of current regional conservation practice to protection of EGS was evaluated, a brief overview of the weak points and the proposal of preciseadaptation measures that should be taken in Vojvodina are presented in final chapter. The results of this study propose the development of spatial adaption measures and conservation design that will contribute not only in preserving EGS and habitats it relay on but also other wild plant and animal species in this intensively used agricultural settings.</p>
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